>> If I use the controls in a single threaded program - no problem.
>> If I use them in a multi-threaded program the simplest call to either
>> causes an exception.

>At least you know that your ActiveX is working.

>> Previous replies indicated that calls to CoInitialize and
>> Couninitialize are required to get the apartment model correct before
>> the calls in to controls could succeed. I tried this and got the same
>> exceptions.

>Well it's more of a security then anything else. The worst case scenario
>with a missing apartment is that you will not be able to create a COM
>component or the called to the method of the component will always fail.

>When you include an ActiveX in a project, it will automatically have an
>apartment ready for you. However i find it annoying since the same won't
>happen in a standard COM component.

>So good rule of thumb is always create an apartement for each new thread or
>process.

>> Perhaps I did not make the calls to init COM correctly or perhaps
>> there is another way to accomplish this feat. Can anyone enlighten
>> me??

>Well if i recall correctly you create a new activeX for each thread right?
>The only problem i could see is if the ocx is single thread only (meaning
>only one thread can ever access the file at anytime). I suppose in that case
>the activeX create would fail for the second thread (never test that so i
>don't know)

>Another point to consider is that you probably use the class wrapper of the
>activeX and not an interface pointer. A class wrapper use the dispatch
>interfafe with the Invoke method to call indirectly the method of the
>activeX. That's automation. One big problem with automation is that you are
>never sure if you either invoke the proper method with the proper
>attributes. You will tend to get a lot of access violation which are of no
>help while debugging.

>It might be good to actually use a raw interface pointer on your activeX and
>try if it makes a difference.

>In each thread you could try this instead :

>    IYourActiveX* pActiveX = 0;
>    HRESULT hr;

>    // The thread start
>    CoInitialize(0);

>    // Create the activeX, you will have to replace the GUID_ and the IID_
>with the proper value of your activeX
>    hr = CoCreateInstance(GUID_YourActiveX, 0, CLSCTX_ALL, IID_YourActiveX,
>reinterpret_cast<void**>(&pActiveX));

>    if( SUCCEEDED(hr) )
>    {
>        // Call some method
>        pActiveX->SomeMethod();

>        // Do other stuff

>        // Eventually we are done
>        pActiveX->Release();
>    }

>    // And the thread is gone
>    CoUinitiliaze();

>    Doing so you can check the hr value if you are able to create the
>activeX or not and the return value can even be decoded with a microsoft
>utility so that can help you know what's going on.

>Hope this helps.

>Francois Belair